Tropical Storm ANA

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TROPICAL STORM ANA DISCUSSION NUMBER 9
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT TUE APR 22 2003
THE INITIAL MOTION IS 080/16. THERE IS NO SIGNIFICANT CHANGE TO THE
PREVIOUS FORECAST TRACK OR REASONING. ANA REMAINS ON COURSE AND IS
BEING STEERED EASTWARD BY DEEP-LAYERED WESTERLY FLOW. MOST OF THE
GLOBAL MODELS AND THE GFDL MODEL GRADUALLY LIFT THE CYCLONE SLOWLY
POLEWARD WITH TIME AS THE PRESENT AMPLIFIED FLOW PATTERN SLOWLY
BREAKS DOWN AND BECOMES MORE ZONAL...WHILE ALSO SHIFTING SLOWLY
NORTHWARD. THE RESULT IS THAT A GENERAL EAST-NORTHEASTWARD MOTION IS
EXPECTED FOR THE NEXT 72 HOURS...THEN BECOMING MORE NORTHEASTWARD BY
DAYS 4 AND 5 AS THE DOWNSTREAM LONGWAVE TROUGH NORTH OF THE AZORES
AMPLIFIES AND DIGS SOUTHWARD TO THE WEST OF THE CYCLONE. HOWEVER...
BY THAT TIME ANA IS EXPECTED TO BE AN EXTRATROPICAL LOW AS IT BEGINS
TO MERGE WITH A FRONTAL SYSTEM BY ABOUT 72 HOURS.
THE INITIAL INTENSITY HAS BEEN DECREASED TO 40 KT. CONVECTION HAS
WAXED AND WANED MOST OF THE DAY...BUT HAS MADE A BRIEF COMEBACK TO
THE NORTHEAST OF THE CENTER DURING THE PAST FEW HOURS. HOWEVER...THE
OVERALL TREND HAS BEEN FOR A DECREASE IN CONVECTION AND THIS IS
INDICATED BY THE LATEST SATELLITE INTENSITY ESTIMATES OF 45 KT...35
KT...AND 30 KT FROM SAB...AFWA...AND TAFB...RESPECTIVELY. SINCE ANA
IS EXPECTED TO SLOW DOWN SIGNIFICANTLY BY 24 HOURS...THE CYCLONE IS
MAINTAINED AS A TROPICAL SYSTEM THROUGH 48 HOURS SINCE CONVECTION
AND A CONDITIONALLY UNSTABLE APPEAR TO LIE AHEAD OF THE SYSTEM AS
FAR EAST AS ABOUT 45W LONGITUDE. EAST OF THAT...HOWEVER...AN
EXTRATROPICAL LOW CURRENTLY WEST OF THE AZORES HAS NO CONVECTION
ASSOCIATED WITH IT...AND THAT WILL PROBABLY BE THE CASE WITH ANA
ONCE IT REACHES THAT SAME REGION BY 72 HOURS...IF NOT SOONER. THE
SHIPS MODEL DISSIPATES ANA IN 36 HOURS AND THAT IS A VIABLE
POSSIBILITY GIVEN THE STRONG SHEAR THAT WILL AFFECT THE CYCLONE.
FORECASTER STEWART
FORECAST POSITIONS AND MAX WINDS
INITIAL 23/0300Z 30.2N 53.9W 40 KTS
12HR VT 23/1200Z 30.9N 51.3W 40 KTS
24HR VT 24/0000Z 31.5N 48.1W 40 KTS
36HR VT 24/1200Z 31.9N 45.3W 40 KTS
48HR VT 25/0000Z 32.2N 42.8W 35 KTS
72HR VT 26/0000Z 33.0N 35.5W 35 KTS...BECOMING EXTRATROPICAL
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